Preparing hides and skins for tanning processes.



EMILE DHUART, 0F LUXEMBURG'.

PREPARING HIDES AND SKINS FOR TANNING PROCESSES.

N 0 Drawing.

To all whom it may concern Be it known that I, EMILE DHUART, a subject of the Grand Duchess of Luxemburg, residing in Luxemburg, have invented certain new and useful Improvements in Preparing Hides and Skins for Tanning Processes, of which. the following is a specification.

This invention relates to a new process for bating skins or hides, applicable in a slightly modified form I for grounding or bating tanned skins or'hides.

-By the invention hides or skins which have been unhaired are bated for the purpose of removing the depilatory, with the glycerol ester of phosphoric acid or an alkali salt or alkaline earth salt thereof. The invention is particularly applicable when barium hydrate or strontium hydrate is the depilatory, although it is also advanta-.

geous when lime has been used. It is convenient to retain the term de-liming for expressing the action of the bate whichever depilatory has been used. This ester forms with the hydrates of calcium, barium and strontium compounds of the alkaline earths which are easily soluble in water and is therefore able completely to separate the last traces of the alkaline earth hydrates from the hide. This is the more necessary because as is known even the smallest residual alkali earth hydrate in the hide im-, parts to the latter undesirable properties.

The bate may be prepared by dissolving in a suitable proportion of water either free glycerophosphoric acid or, according to the kind of skin under treatment, glycerophosphate of sodium, potassium, or ammonium, so that the skin under treatment may be subjected to the acid bate alone, or to the alkaline bate alone, or even as may be desirable, to the alkaline bate and the acid hate in succession.

In the case of heavy hides and skins which leave the unhairing pits impregnated with much alkaline earth, the bath may consist of a solution of free glycerophosphoric acid which will speedily become neutralized by the alkaline earth which it dissolves from the hide. In the case of lighter skins, how

ever, it is generally advisable to use a bath containing a solution of an alkali .or alkaline phosphoric acid, which have at. the same Specification of Letters Patent.

an alkali salt has been added. 7

Patented Feb. i, 1916.

Application filed June 18, 1914. Serial No. 845,747.

time a solvent action on albumin, may under certain conditions be advantageously enhanced by small additions of alkali bicarbonate, ammonium nitrate or ammonium salts of volatile fatty acids forkeeping the hide or skin soft as well as for completely separating the strontium and barium compounds remaining in thehide. The glycerophosphoric acid de-liming bate has the additional advantage that it plumps the hide or skin and makes it soft, pliable and smooth, while it produces a de-liming which is all the more complete because the hate itself has the property of dissolving amorphous albuminous substances and in this manner a rational emptying of the pores of v the hide is effected. After this treatment the hide or skin proceeds to the bran drench and is then prepared for tanning.

The advantages of the preparatory process just described may be summed up as follows :-1. As the materials used for the production ofthebates are soluble in water, unhairing andde-liming proceed in clear solutions and can easily be controlled at any time; they are also carried through in minimum time to rational results. 2. The particular advantage of using baryta or strontium as the depilatory when gylcerophosphoric acid is used as a bate resides in the possibility presented of revivifying the spent glycerophosphate bath by adding an equivalent proportion of sulfuric acid and subsequently clarifying the bath to remove the insoluble sulfate.

When the baths have become charged with organic matter by repeated use they may finally be used for the production of phosphatic manure by addition of lime.

Having thus described the nature of 'this invention and the best means I know of carrying the same into practical effect, I claim 1. A process for hating unhaired skins, which consists in subjecting the skin to the action of free glycerophosphoric acid.

2. A' process for hating unhaired skins, which consists in subjecting the skinto the action of free glycerophosphoric acid, and

- afterward to the action of analkali glycerophosphate salt.

3. A process for hating unhaired skins,

i which consists'in subjecting the skin;to-Ithe action of glycerophosphoric acid to whicl 4. A process for hating unhaired skins, which consists in subjecting the skin to the action of glycerophosphoric acid to which an alkali salt has been added, and afterward tolthe action of an alkali glycerophosphate sa t.

5. A tanning process which consists in unhairing the skin with the aid of a concentrated solution of analkaline earth such as barium hydrate and subsequently hating the 10 skinby the action of free glycerophosphoric acid.

In testimony whereof I have signed my name to this specification.

EMILE DHUART; 

